Cytoskeleton/stretch-activated ion channel interaction regulates myogenic differentiation of skeletal myoblasts

In the present study, we investigated the functional interaction between stress fibers (SFs) and stretch-activated channels (SACs) and its possible role in the regulation of myoblast differentiation induced by switch to differentiation culture in the presence or absence of sphingosine 1-phosphate. It was found that there was a clear temporal correlation between SF formation and SAC activation in differentiating C2C12 myoblasts. Inhibition of actin polymerization with the specific Rho kinase inhibitor Y-27632, significantly decreased SAC sensitivity in these cells, suggesting a role for Rho-dependent actin remodeling in the regulation of the channel opening. The alteration of cytoskeletal/SAC functional correlation had also deleterious effects on myogenic differentiation of C2C12 cells as judged by combined confocal immunofluorescence, biochemical and electrophysiological analyses. Indeed, the treatment with Y-27632 or with DHCB, an actin disrupting agent, inhibited the expression of the myogenic markers (myogenin and sarcomeric proteins) and myoblast-myotube transition. The treatment with the channel blocker, GdCl(3), also affected myogenesis in these cells. It impaired, in fact, myoblast phenotypic maturation (i.e., reduced the expression of alpha-sarcomeric actin and skeletal myosin and the activity of creatine kinase) but did not modify promoter activity and protein expression levels of myogenin. The results of this study, together with being in agreement with the general idea that cytoskeletal remodeling is essential for muscle differentiation, describe a novel pathway whereby the formation of SFs and their contraction, generate a mechanical tension to the plasma membrane, activate SACs and trigger Ca(2+)-dependent signals, thus influencing the phenotypic maturation of myoblasts.     

Stiffness changes in cultured airway smooth muscle cells

Airwaysmooth muscle (ASM) cells in culture stiffen when exposed tocontractile agonists. Such cell stiffening may reflect activation ofthe contractile apparatus as well as polymerization of cytoskeletalbiopolymers. Here we have assessed the relative contribution of thesemechanisms in cultured ASM cells stimulated with serotonin(5-hydroxytryptamine; 5-HT) in the presence or absence of drugs thatinhibit either myosin-based contraction or polymerization offilamentous (F) actin. Magnetic twisting cytometry was used to measurecell stiffness, and associated changes in structural organization ofactin cytoskeleton were evaluated by confocal microscopy. We found that5-HT increased cell stiffness in a dose-dependent fashion and alsoelicited rapid formation of F-actin as marked by increased intensity ofFITC-phalloidin staining in these cells. A calmodulin antagonist (W-7),a myosin light chain kinase inhibitor (ML-7) and a myosin ATPaseinhibitor (BDM) each ablated the stiffening response but not theF-actin polymerization induced by 5-HT. Agents that inhibited theformation of F-actin (cytochalasin D, latrunculin A, C3 exoenzyme, andY-27632) attenuated both baseline stiffness and the extent of cellstiffening in response to 5-HT. Together, these data suggest thatagonist-evoked stiffening of cultured ASM cells requires actinpolymerization as well as myosin activation and that neitheractin polymerization nor myosin activation by itself is sufficient toaccount for the cell stiffening response.

     

Phosphorylation of myosin light chain during capping of mouse T- lymphoma cells

Colchicine induces the clustering of at least three different T- lymphoma surface antigens (T200, Thy-1, and gp 69/71) into a cap structure in the absence of any external ligand. In addition, colchicine induces the intracellular accumulation of actin and myosin directly beneath the surface cap structure. We have discovered that myosin molecules (both heavy and light chains) are closely associated with the plasma membrane of T-lymphoma cells. Most importantly, we have found that the 20,000-dalton light chain of lymphocyte myosin is both phosphorylated and preferentially accumulated in the plasma membrane of colchicine-induced capped cells. It is proposed that myosin light chain is directly involved in the activation of membrane-associated actomyosin required for the collection of surface proteins into a cap structure (analogous to muscle cell sliding filament contraction).     

Migration of zebrafish primordial germ cells: a role for myosin contraction and cytoplasmic flow

The molecular and cellular mechanisms governing cell motility and directed migration in response to the chemokine SDF-1 are largely unknown. Here, we demonstrate that zebrafish primordial germ cells whose migration is guided by SDF-1 generate bleb-like protrusions that are powered by cytoplasmic flow. Protrusions are formed at sites of higher levels of free calcium where activation of myosin contraction occurs. Separation of the acto-myosin cortex from the plasma membrane at these sites is followed by a flow of cytoplasm into the forming bleb. We propose that polarized activation of the receptor CXCR4 leads to a rise in free calcium that in turn activates myosin contraction in the part of the cell responding to higher levels of the ligand SDF-1. The biased formation of new protrusions in a particular region of the cell in response to SDF-1 defines the leading edge and the direction of cell migration.     

Regulation of cell contraction and membrane ruffling by distinct signals in migratory cells.

Cell migration and wound contraction requires assembly of actin into a functional myosin motor unit capable of generating force. However, cell migration also involves formation of actin-containing membrane ruffles. Evidence is provided that actin-myosin assembly and membrane ruffling are regulated by distinct signaling pathways in the migratory cell. Interaction of cells with extracellular matrix proteins or cytokines promote cell migration through activation of the MAP kinases ERK1 and ERK2 as well as the molecular coupling of the adaptor proteins p130CAS and c-CrkII. ERK signaling is independent of CAS/Crk coupling and regulates myosin light chain phosphorylation leading to actin-myosin assembly during cell migration and cell-mediated contraction of a collagen matrix. In contrast, membrane ruffling, but not cell contraction, requires Rac GTPase activity and the formation of a CAS/Crk complex that functions in the context of the Rac activating protein DOCK180. Thus, during cell migration ERK and CAS/Crk coupling operate as components of distinct signaling pathways that control actin assembly into myosin motors and membrane ruffles, respectively.     

Myosin ii light chain phosphorylation regulates membrane localization and apoptotic signaling of tumor necrosis factor receptor-1

Activation of myosin II by myosin light chain kinase (MLCK) produces the force for many cellular processes including muscle contraction, mitosis, migration, and other cellular shape changes. The results of this study show that inhibition or potentiation of myosin II activation via over-expression of a dominant negative or wild type MLCK can delay or accelerate tumor necrosis factor-alpha (TNF)-induced apoptotic cell death in cells. Changes in the activation of caspase-8 that parallel changes in regulatory light chain phosphorylation levels reveal that myosin II motor activities regulate TNF receptor-1 (TNFR-1) signaling at an early step in the TNF death signaling pathway. Treatment of cells with either ionomycin or endotoxin (lipopolysaccharide) leads to activation of myosin II and increased translocation of TNFR-1 to the plasma membrane independent of TNF signaling. The results of these studies establish a new role for myosin II motor activity in regulating TNFR-1-mediated apoptosis through the translocation of TNFR-1 to or within the plasma membrane.     

Functional coupling of ion channels in cellular mechanotransduction

The major players in the processes of cellular mechanotransduction are considered to be mechanosensitive (MS) or mechano-gated ion channels. Non-selective Ca²⁺-permeable channels, whose activity is directly controlled by membrane stretch (stretch-activated channels, SACs) are ubiquitously present in mammalian cells of different origin. Ca²⁺ entry mediated by SACs presumably has a significant impact on various Ca²⁺-dependent intracellular and membrane processes. It was proposed that SACs could play a crucial role in the different cellular reactions and pathologies, including oncotransformation, increased metastatic activity and invasion of malignant cells. In the present work, coupling of ion channels in transformed fibroblasts in course of stretch activation was explored with the use of patch-clamp technique. The combination of cell-attached and inside-out single-current experiments showed that Ca²⁺ influx via SACs triggered the activity of Ca²⁺-sensitive K⁺ channels indicating functional compartmentalization of different channel types in plasma membrane. Importantly, the analysis of single channel behavior demonstrated that K⁺ currents could be activated by the rise of intracellular calcium but displayed no direct mechanosensitivity. Taken together, our data imply that local changes in Ca²⁺ concentration due to SAC activity may provide a functional link between various Ca²⁺-dependent molecules in the processes of cellular mechanotransduction.     

Complement C5b-9-stimulated platelet secretion is associated with a Ca2+-initiated activation of cellular protein kinases

Membrane assembly of the C5b-9 proteins on gel-filtered human platelets has been shown to initiate the nonlytic release of alpha-granule contents and expression of membrane prothrombinase sites, suggesting cellular activation by these ostensibly cytolytic plasma proteins (Wiedmer, T., Esmon, C. T., and Sims, P. J. (1986) J. Biol. Chem. 261, 14587-14592). We now examine the mechanism of the C5b-9-induced release reaction. The release of alpha-granule contents upon C5b-9 assembly is accompanied by expression of alpha-granule membrane glycoprotein 140 on the platelet surface, confirming that the complement-mediated release reaction occurs by secretory fusion of the alpha-granule with the plasma membrane. C5b-9 binding initiates the phosphorylation of both 40- and 20-kDa platelet proteins, indicative of activation of protein kinase C and myosin light chain kinase, respectively. Activation of cellular protein kinases under these conditions was not accompanied by the formation of inositol phosphates and was found to strictly depend upon extracellular Ca2+, suggesting that the platelet's secretory response to the C5b-9 proteins is triggered directly by the influx of Ca2+ across the plasma membrane. measurement of intracellular Ca2+ confirmed that elevation of this ion in the cytosol was strictly dependent upon increased plasma membrane permeability due to C5b-9 assembly and was not accompanied by mobilization of this ion from internal storage pools. The C5b-9-mediated secretory response was blocked by sphingosine, a potent inhibitor of protein kinase C, but was unaffected by the cyclooxygenase inhibitor indomethacin, suggesting that feedback (receptor-linked) by thromboxane is not required for platelet activation after C5b-9 insertion.     

Cholesterol depletion-induced inhibition of stretch-activated channels is mediated via actin rearrangement

Cholesterol is a critical regulator of lipid bilayer dynamics and plasma membrane organization in eukaryotes. A variety of ion channels have been shown to be modulated by cellular cholesterol and partition into cholesterol-enriched membrane rafts. However, very little is known about functional role of membrane cholesterol in regulation of mechanically gated channels that are ubiquitously present in living cells. In our previous study, the effect of methyl-beta-cyclodextrin (MbCD), cholesterol-sequestering agent, on Ca²⁺-permeable stretch-activated cation channels (SACs) has been described. Here, cell-attached patch-clamp method was employed to search for the mechanisms of cholesterol-dependent regulation of SACs and to clarify functional contribution of lipid bilayer and submembranous cytoskeleton to channel gating. Cholesterol-depleting treatment with MbCD significantly decreased open probability of SACs whereas alpha-cyclodextrin had no effect. F-actin disassembly fully restored high level of SAC activity in cholesterol-depleted cells. Particularly, treatment with cytochalasin D or latrunculin B abrogated inhibitory effect of MbCD on stretch-activated currents. Single channel analysis and fluorescent imaging methods indicate that inhibition of SACs after cholesterol depletion is mediated via actin remodeling initiated by disruption of lipid rafts. Our data reveal a novel mechanism of channel regulation by membrane cholesterol and lipid rafts.     

Polarized Sphingolipid Transport from the Subapical Compartment: Evidence for Distinct Sphingolipid Domains

In polarized HepG2 cells, the sphingolipids glucosylceramide and sphingomyelin (SM), transported along the reverse transcytotic pathway, are sorted in subapical compartments (SACs), and subsequently targeted to either apical or basolateral plasma membrane domains, respectively. In the present study, evidence is provided that demonstrates that these sphingolipids constitute separate membrane domains at the luminal side of the SAC membrane. Furthermore, as revealed by the use of various modulators of membrane trafficking, such as calmodulin antagonists and dibutyryl-cAMP, it is shown that the fate of these separate sphingolipid domains is regulated by different signals, including those that govern cell polarity development. Thus under conditions that stimulate apical plasma membrane biogenesis, SM is rerouted from a SAC-to-basolateral to a SAC-to-apical pathway. The latter pathway represents the final leg in the transcytotic pathway, followed by the transcytotic pIgR-dIgA protein complex. Interestingly, this pathway is clearly different from the apical recycling pathway followed by glucosylceramide, further indicating that randomization of these pathways, which are both bound for the apical membrane, does not occur. The consequence of the potential coexistence of separate sphingolipid domains within the same compartment in terms of "raft" formation and apical targeting is discussed.     

Ion mechanisms of the mechanoelectrical feedback in myocardial cells

This article is dedicated to the mechanism of mechano-electric feedback in heart. The evidence is briefly discussed on organ, tissue, cell and in details on cell membrane levels in case of application of one of applied mechanical stimulus to cardiomyocytes. Stretch of the hole heart or its tissue fragment causes quick starting repolarization of action potentials (AP)/monophasic action potentials (MAP), shift of AP/MAP plato to higher negative zone, appearance of peaks of stretch-induced depolarization (SID) on final phase of AP/MAP repolarization level, which are overgrowing into extra AP/extra MAP. Mechanical events (changes in length and force of contractions) change electrical processes by means of direct influence on cell membrane via stretch activated channels (SAC). Cardiomyocytes, isolated from animal atrium and animal and human ventricular are responsible for the stretch of depolarized membrane, prolongation of AP and appearance of extra AP (extra systoles). Analysis of experiments, conducted following the patch clamp method in whole cell configuration, shows that the main cause of that mechanical events is SAC current--ISAC. During negative potential ISAC is determined by incoming into the cell sodium ions and is negative. Negative ISAC is changing final phase of AP/MAP repolarization and causes SID, which is overgrowing into extra AP (extra systoles), in case that SID exceeds threshold. Fast AP repolarization and AP plato shift into higher negative zone is related to positive ISAC (living potassium ions through SAC), activation of IK and reduction of ISAC. Activation of ISAC and arrhythmia induction require lower mechanical stimulus for hypertrophied cardiomyocytes, in comparisment to healthy ones. Hypertrophy of cardiomyocytes can lead to expression of SAC therefore increasing channel density and ISAC maximum amplitude. In this article is discussing data, acquired by means of direct measurement of conduction of single SAC on the background of mechanical stimulation of the cardiomyocytes membrane. It contains characteristics of the estimated SACs. It is shown that blocking of conduction of ions through SAC prevents mechanically induced arrhythmia in healthy and hypertrophied cardiomyocytes, which transforms the problem of mechano-electric feedback in heart from purely fundamental into clinical one.     

Protein kinase C in the regulation of smooth muscle contraction

The cellular and molecular mechanisms underlying smooth muscle contraction are reviewed in the light of recent studies of smooth muscle ultrastructure and of the role of polyphosphoinositide turnover and protein kinase C function in smooth muscle contraction. A new model of smooth muscle contraction is proposed that differs radically from accepted views, particularly the latch bridge hypothesis, in terms of both Ca2+ messenger function and the molecular events underlying this process. A coordinate fibrillar domain model of contraction is proposed in which the initial and sustained phases of contraction are mediated by different cellular and molecular events. The initial phase of response is mediated by a rise in [Ca2+]c and the resulting calmodulin-dependent activation of both myosin light chain kinase and the dissociation of caldesmon from the actin-caldesmon-tropomyosin-myosin fibrillar domain. These events lead to an interaction between actin and the phosphorylated light chains of myosin just as in previous models. However, this initial phase is followed by a sustained phase in which a rise in [Ca2+]sm stimulates the plasma membrane-associated, Ca2+-sensitive form of protein kinase C that results in the phosphorylation of both structural and regulatory components of the filamin-actin-desmin fibrillar domain. These events underlie the tonic phase of contraction.     

Galphaq-TRPC6-mediated Ca2+ entry induces RhoA activation and resultant endothelial cell shape change in response to thrombin

RhoA activation and increased intracellular Ca(2+) concentration mediated by the activation of transient receptor potential channels (TRPC) both contribute to the thrombin-induced increase in endothelial cell contraction, cell shape change, and consequently to the mechanism of increased endothelial permeability. Herein, we addressed the possibility that TRPC signals RhoA activation and thereby contributes in actinomyosin-mediated endothelial cell contraction and increased endothelial permeability. Transduction of a constitutively active Galphaq mutant in human pulmonary arterial endothelial cells induced RhoA activity. Preventing the increase in intracellular Ca2+ concentration by the inhibitor of Galphaq or phospholipase C and the Ca2+ chelator, BAPTA-AM, abrogated thrombin-induced RhoA activation. Depletion of extracellular Ca2+ also inhibited RhoA activation, indicating the requirement of Ca2+ entry in the response. RhoA activation could not be ascribed to storeoperated Ca2+ (SOC) entry because SOC entry induced with thapsigargin or small interfering RNA-mediated inhibition of TRPC1 expression, the predominant SOC channel in these endothelial cells, failed to alter RhoA activity. However, activation of receptor-operated Ca2+ entry by oleoyl-2-acetyl-sn-glycerol, the membrane permeable analogue of the Galphaq-phospholipase C product diacylglycerol, induced RhoA activity. Receptor-operated Ca2+ activation was mediated by TRPC6 because small interfering RNA-induced TRPC6 knockdown significantly reduced Ca2+ entry. TRPC6 knockdown also prevented RhoA activation, myosin light chain phosphorylation, and actin stress fiber formation as well as inter-endothelial junctional gap formation in response to either oleoyl-2-acetyl-sn-glycerol or thrombin. TRPC6-mediated RhoA activity was shown to be dependent on PKCalpha activation. Our results demonstrate that Galphaq activation of TRPC6 signals the activation of PKCalpha, and thereby induces RhoA activity and endothelial cell contraction.     

Membrane blebbing during apoptosis results from caspase-mediated activation of ROCK I

The execution phase of apoptosis is characterized by marked changes in cell morphology that include contraction and membrane blebbing. The actin-myosin system has been proposed to be the source of contractile force that drives bleb formation, although the biochemical pathway that promotes actin-myosin contractility during apoptosis has not been identified. Here we show that the Rho effector protein ROCK I, which contributes to phosphorylation of myosin light-chains, myosin ATPase activity and coupling of actin-myosin filaments to the plasma membrane, is cleaved during apoptosis to generate a truncated active form. The activity of ROCK proteins is both necessary and sufficient for formation of membrane blebs and for re-localization of fragmented DNA into blebs and apoptotic bodies.     

Isolation of concanavalin a caps during various stages of formation and their association with actin and myosin

Regions of plasma membrane of dictyostelium discoideum amoebae that contain concanavalin A (Con A)-receptor complexes are more resistant to disruption by Triton X-100. This resistance makes possible the isolation of Con A-associated membrane fragments in sufficient quantity and homogeneity to permit the direct biochemical and ultrastructural study of receptor-cytoskeletal interactions across the cell membrane. After specific binding of Con A to the cell surface, a large amount of the cell’s actin and myosin copurifies with the plasma membrane fragments. Myosin is more loosely bound to the isolated membranes that actin and is efficiently removed by treating membranes with ATP and low ionic strength. If cells are not lysed immediately after lectin binding, all of the Con A that is bound to the cell surface is swept into a cap in a process requiring metabolic energy. When cells are lysed at different stages of cap formation, the amount of actin and myosin that copurifies with the isolated membranes remains the same. Thick and thin filaments that are attached to the protoplasmic surface of the isolated membranes underlie lectin-receptor complexes during all stages of cap formation. Once the cap is complete, the amount of actin and myosin that tightly bound to the plasma membrane is concentrated into the cap along with the Con A-receptor complexes. These results suggest that the ATP-dependent sliding of membrane-associated actin and myosin filaments is responsible for the accumulation of Con A-receptor complexes into a cap on the cell surface.     

Wnt/Frizzled signaling controls C. elegans gastrulation by activating actomyosin contractility

BACKGROUND: Embryonic patterning mechanisms regulate the cytoskeletal machinery that drives morphogenesis, but there are few cases where links between patterning mechanisms and morphogenesis are well understood. We have used a combination of genetics, in vivo imaging, and cell manipulations to identify such links in C. elegans gastrulation. Gastrulation in C. elegans begins with the internalization of endodermal precursor cells in a process that depends on apical constriction of ingressing cells. RESULTS: We show that ingression of the endodermal precursor cells is regulated by pathways, including a Wnt-Frizzled signaling pathway, that specify endodermal cell fate. We find that Wnt signaling has a role in gastrulation in addition to its earlier roles in regulating endodermal cell fate and cell-cycle timing. In the absence of Wnt signaling, endodermal precursor cells polarize and enrich myosin II apically but fail to contract their apical surfaces. We show that a regulatory myosin light chain normally becomes phosphorylated on the apical side of ingressing cells at a conserved site that can lead to myosin-filament formation and contraction of actomyosin networks and that this phosphorylation depends on Wnt signaling. CONCLUSIONS: We conclude that Wnt signaling regulates C. elegans gastrulation through regulatory myosin light-chain phosphorylation, which results in the contraction of the apical surface of ingressing cells. These findings forge new links between cell-fate specification and morphogenesis, and they represent a novel mechanism by which Wnt signaling can regulate morphogenesis.     

Molecular Mechanisms of Thrombin-Induced Endothelial Cell Permeability

Confluent endothelium serves as a selective barrier between the vascular space of blood vessels and underlying tissues. Compromised barrier function of the endothelium in response to inflammation mediators, such as thrombin, is accompanied by reversible cell rounding and interendothelial gap formation. Endothelial barrier integrity substantially depends on the cytoskeleton, which ensures actin stress fiber formation and via actomyosin-driven contraction regulates cell shape and adhesion. Recent studies have shown the sequence of events that mediate signal transduction in endothelial cells. Binding of thrombin with its receptor initiates activation of heterotrimeric G-proteins, which, in turn, entails a decrease in cAMP level in the cell, increase in intracellular Ca²⁺ and diacylglycerol concentration, and activation of the small G-protein Rho. Phosphorylation of myosin light chains as a result of activation of myosin light chain kinase and inactivation of myosin phosphatases stimulates stress fiber formation and triggers actomyosin contraction. In addition, thrombin-induced rearrangement in the endothelial cytoskeleton is regulated by Ca²⁺/calmodulin-dependent protein kinase, protein kinase C, and tyrosine protein kinases. This review focuses on presently known biochemical mechanisms of cell response to thrombin and their role in endothelial barrier dysfunction.     

Is the Cross-Bridge Stiffness Proportional to Tension during Muscle Fiber Activation?

The cross-bridge stiffness can be used to estimate the number of S1 that are bound to actin during contraction, which is a critical parameter for elucidating the fundamental mechanism of the myosin motor. At present, the development of active tension and the increase in muscle stiffness due to S1 binding to actin are thought to be linearly related to the number of cross-bridges formed upon activation. The nonlinearity of total stiffness with respect to active force is thought to arise from the contribution of actin and myosin filament stiffness to total sarcomere elasticity. In this work, we reexamined the relation of total stiffness to tension during activation and during exposure to N-benzyl-p-toluene sulphonamide, an inhibitor of cross-bridge formation. In addition to filament and cross-bridge elasticity, our findings are best accounted for by the inclusion of an extra elasticity in parallel with the cross-bridges, which is formed upon activation but is insensitive to the subsequent level of cross-bridge formation. By analyzing the rupture tension of the muscle (an independent measure of cross-bridge formation) at different levels of activation, we found that this additional elasticity could be explained as the stiffness of a population of no-force-generating cross-bridges. These findings call into question the assumption that active force development can be taken as directly proportional to the cross-bridge number.     

Spatial organization and fine structure of the cortical filament layer in normal locomoting Amoeba proteus

Summary The fine structural organization of a cortical filament layer in normal locomoting Amoeba proteus was demonstrated using improved fixation and embedding techniques. Best results were obtained after application of PIPES-buffered glutaraldehyde in connection with substances known to prevent the depolymerization of F-actin, followed by careful dehydration and freeze-substitution.The filament layer is continuous along the entire surface; it exhibits a varying thickness depending on the cell polarity, measuring several nm in advancing regions and 0.5–1 m in retracting ones. Two different types of filaments are responsible for the construction of the layer: randomly distributed thin (actin) filaments forming an unordered meshwork beneath the plasma membrane, and thick (myosin) filaments mostly restricted to the uroid region in close association with F-actin.The cortical filament layer generates the motive force for amoeboid movement by contraction at posterior cell regions and induces a pressure flow that continues between the uroid with a high hydrostatic pressure and advancing pseudopodia with a low one. The local destabilization of the cell surface as a precondition for the formation of pseudopodia is enabled by the detachment of the cortical filament layer from the plasma membrane. This results in morphological changes by the active separation of peripheral hyaloplasmic and central granuloplasmic regions.     

Oncostatin M-stimulated apical plasma membrane biogenesis requires p27(Kip1)-regulated cell cycle dynamics

Oncostatin M regulates membrane traffic and stimulates apicalization of the cell surface in hepatoma cells in a protein kinase A-dependent manner. Here, we show that oncostatin M enhances the expression of the cyclin-dependent kinase (cdk)2 inhibitor p27(Kip1), which inhibits G(1)-S phase progression. Forced G(1)-S-phase transition effectively renders presynchronized cells insensitive to the apicalization-stimulating effect of oncostatin M. G(1)-S-phase transition prevents oncostatin M-mediated recruitment of protein kinase A to the centrosomal region and precludes the oncostatin M-mediated activation of a protein kinase A-dependent transport route to the apical surface, which exits the subapical compartment (SAC). This transport route has previously been shown to be crucial for apical plasma membrane biogenesis. Together, our data indicate that oncostatin M-stimulated apicalization of the cell surface is critically dependent on the ability of oncostatin M to control p27(Kip1)/cdk2-mediated G(1)-S-phase progression and suggest that the regulation of apical plasma membrane-directed traffic from SAC is coupled to centrosome-associated signaling pathways.